Vinyl chloride (CH.sub.2 .dbd.CHCl) is prepared using a number of well known processes. Two familiar processes are (1) the hydrochlorination of acetylene and (2) the oxychlorination of ethylene to form dichloroethane which in turn is dehydrohalogenated to form vinyl chloride (see C. A. Schildknecht, Vinyl and Related Polymers, John Wiley and Sons, Inc., N.Y., N.Y. (1952), pages 388-390 and U.S. Pat. No. 2,847,483). As acetylene is more expensive than ethylene, the latter process is economically favored, and much activity is noted in this art area (see U.S. Pat. Nos. 3,634,330; 3,454,663; 3,448,057; and 3,624,170). Ethylene, in turn, can be prepared by the oxydehydrogenation of ethane (see U.S. Pat. No. 3,769,362). Although high yields of ethylene are particularly desired, processes which use ethane as a feed stock can produce not only ethylene, but also can directly produce vinyl chloride and other valuable products such as ethylene dichloride, ethyl chloride, and the like. The ethylene, ethylene dichloride, and ethyl chloride can be readily reacted to form more vinyl chloride.
The present invention is directed to an improved process for the preparation of ethylene and vinyl chloride from ethane which improvement comprises the in situ regeneration of a solid solution catalyst containing iron by the addition of an iron source to the ongoing process.
Catalysts containing iron are known in the art. See U.S. Pat. Nos. 3,907,713; 3,849,339; 3,769,362; 3,703,593; 3,658,934; 3,658,933; 3,207,811; 2,847,483; and 2,674,633, and British Patent No. 1,039,369. However, none of these patents disclose a solid solution catalyst. An article in the Journal of the American Ceramic Society, Vol. 43, No. 7 (1960), page 367, discloses ceramic compounds of lanthanum and iron. Two patents directed to the desirability of using specific supports for a catalyst are U.S. Pat. No. 3,454,663 (an .alpha.-Al.sub.2 O.sub.3 support) and U.S. Pat. No. 3,723,351 (a calcium sodium aluminum disilicate support). Recently issued U.S. Pat. No. 3,904,553 discloses the use of certain specific solid solutions as catalysts.
Known methods of catalyst regeneration include methods where the catalyst is physically removed from the reaction area and treated, often by heating or re-firing the catalyst in an oxidative atmosphere, and methods wherein the catalyst is treated in situ by varying the feed and/or reactant stream to the reactor area. Examples of these methods are disclosed in U.S. Pat. Nos. 3,551,506 and 3,870,764. U.S. Pat. No. 3,870,764 further discloses the post-addition of phosphorous to the reaction zone.
Other art considered in this application other than those patents and articles mentioned above is as follows: U.S. Pat. Nos. 3,173,962; 3,308,188; 3,308,193; 3,308,198; 3,429,901; 3,707,806, 3,707,809; 3,862,996; 3,904,552; 3,907,912; and 3,917,541, and British Patent No. 904,084.